Add remaining oil to pan; cook onions, mushrooms and thyme, stirring occasionally, for about 10 minutes or until mushrooms are golden and liquid is evaporated. Sprinkle with flour, salt and pepper; cook stirring, for 1 minute. Gradually whisk in chicken stock and evaporated milk; cook. Stirring, for 2 minutes or until thickened. Stir in chicken.
Meanwhile, in large pot of boiling salted water, cook pasta for 8-10 minutes or until tender but firm; drain and return to pot. Add sauce and half of the parsley; toss to coat. Serve sprinkled with remaining parsley. Makes 4 servings